Distance calculation apparatus, imaging apparatus, and distance calculation method that include confidence calculation of distance information

A distance calculation apparatus configured to calculate distance information based on a first image, which is generated based on luminous flux that passed through a first pupil region, and a second image, which is generated based on luminous flux that passed through a second pupil region, a center of gravity of the first pupil region and a center of gravity of the second pupil region being located at different positions along a first axis, the distance calculation apparatus comprising:

• a distance calculation unit configured to calculate the distance information by comparing a local region of the first image and a local region of the second image;
• and
• a confidence calculation unit configured to calculate, for a plurality of times, a first value, which indicates a contrast change amount along the first axis, in a second axis direction crossing the first axis, in the local region of the first image, in the local region of the second image, or in a local region of a composite image of the first image and the second image, and to calculate confidence of the distance information based on a second value, which is a value representing the plurality of first values.